Turbocharged (TC) spark-ignited (SI) engines are popular as they combine high power output with good fuel economy. Furthermore, their emissions can be successfully reduced using a three way catalyst (TWC) provided that the airfuel ratio is precisely controlled. As the air-fuel ratio depends on the precision of the air charge estimate, this thesis is devoted to the systematic improvement of the ...

Laser ignition (LI) has been shown to offer many potential benefits compared to spark ignition (SI) for improving the performance of internal combustion (IC) engines. This paper outlines progress made in recent research on laser ignited IC engines, discusses the potential advantages and control opportunities and considers the challenges faced and prospects for its future implementation. An expe...

This paper investigates optimal strategies for minimising the conflicting objectives of fuel consumption and warm up duration following an engine cold start. Using a reduced order model, parametric solutions for the optimal air-fuel ratio, valve timing, cam timing and idle speed setpoint are sought in the presence of input constraints. The results are then validated using a dynamic programming ...

Simulations of forced ignition of non-premixed laminar counterflow flames are used to study the effect of strain rate on ignition success. A one dimensional calculation is performed, using detailed methane chemical kinetics and treating the spark as an instantaneous heat release in an inert mixing layer. Ignition success depends on the mixture composition at the spark location, resulting in lea...

There are many incentives to increase the fuel efficiency of combustion processes. This paper looks at two available options to achieve this goal. The former aims to develop an experimental method that can analyze combustion at extremely high pressures to improve the understanding of high pressure H2/air combustion. Experimental data has been lacking a suitable combustion diagnostic to visualiz...

Spark-ignition engines exhibit patterns of increasing instability as engine fueling goes from stoichiometric to lean. The observation of time irreversibility in cycleresolved combustion measurements indicates that this combustion instability is inherently nonlinear. Using time return maps and symbolic time-series analysis, we demonstrate the presence of strong time irreversibility in experiment...

Under conditions of lean fueling or high exhaust gas recirculation, interactions between residual cylinder gas and freshly injected fuel and air produce undesirable combustion instabilities in spark-ignition engines. The resulting dynamics can be described as noisy bifurcations of a nonlinear map and are complicated by cylinder-to-cylinder coupling. We discuss the key dynamic features relevant ...

The model developed previously for evaluating the impact of direct ethanol injection on the avoidance of knock in spark ignition engines is used to evaluate the trends of changes in compression ratio and variation in the inlet pressure. The ethanol fraction requirements through the engine map is calculated using detailed chemical kinetics model, and a vehicle simulation is used to determine the...